Conversion of mercaptans



United States Patent 0 No Drawing. Application February 15, 1954, SerialN0. 410,445

10 Claims. (Cl. 196-24) This invention relates to the conversion ofmer'captans E One method utilized for the treatment of petroleumdistillates to remove mercaptans entails the use of an alkaline materialand particularly an alkali metal hydroxide including sodium hydroxide,potassium hydroxide, etc. Modification of this process comprises the useof a solutizer including alcohols, phenols, etc. Other methods includethe copper sweetening process, doctor sweetening process, etc.

In accordance with the present invention, mercaptans are converted byreacting with a particular type of organic compound. While this methodmay be utilized for the conversion of mercaptans as such, it isparticularly advantageous for use in the treatment of organicsubstances, including petroleum fractions, in which the mercaptans arepresent as an undesired impurity.

In a preferred embodiment, a major proportion of the mereaptans areremoved from the petroleum distillate by treatment with an alkali metalhydroxide or otherwise, and the remaining small amount of mercaptans,after such treatment, are converted by means of the novel method of thepresent invention. The major proportion of the mercaptans are readilyremoved in the processes of the prior art but the final sweetening ofthe distillate usually is much more difi'icult. In accordance with thepresent invention, final sweetening is effected by converting theremaining mercaptans in the manner to be hereinafter set forth indetail.

In one embodiment the present invention relates to a method ofconverting a mercaptan which comprises reacting the mercaptan with abeta-dialkylamino ketone.

In a specific embodiment the present invention relates to a method oftreating a sour petroleum distillate which comprises reacting themercaptans contained in the distillate with a beta-dimethylamino ketone.

In another specific embodiment the inve'ntion relates to a method ofsweetening a sour cracked gasoline which com rises reacting themercaptans eofitained ih said gaseline withbeta-diniethylaminopropiophenone.

The beta-dialk'ylamino ketones may be illustrated by the followinggeneral formula:

R1 RO-CCN II where R, R1 and R2 are hydrocarbon groups.

It is understood that R, R1 and R2 may be the same or from 1 to 4 carbonatoms each. Illustrative compounds in which R is an alkyl group includemethyl beta dimethylaminoethyl ketone, ethyl beta-dimethylaminoethylketone, propyl beta-dimethylam'inoethyl ketone, butylbeta-dimethylaminoethyl ketone, amyl beta-dimethylaminoethyl ketone,heXyl heta-dimethylaminoethyl ketone, heptyl beta-dimethylaminoethylketone, octyl betadimethylaminoethyl ketone, etc., methylbeta-diethylaminoethyl ketone, methyl beta-dipropylarninoethyl ke- 1tone, methyl beta-dibut-ylaminoethyl ketone, etc., methylbeta-dimethylaminopropyl ketone, methyl beta-dimethylaminobutyl ketone,methyl beta-dimethylaminoamyl ketone, methyl beta-dimethylaminohexylketone, etc., methyl beta-diethylaminopropyl ketone, methyl beta diethylaininobutyl ketone, methyl beta-diethylaminoamyl ketone, methylbeta-diethylaminohexyl ketone, etc., methyl beta-dipropylaminopropylketone, methyl betadipropylaminobutyl ketone, methylbeta-dipropylaminoamyl ketone, methyl beta-dipropylaminohexyl ketone,etc., methyl beta-dibutylaminopropyl ketone, methylbeta-dibutylaminobutyl ketone, methyl beta-dibutylaminoamyl ketone,methyl beta-dibutylaminohexyl ketone, etc., ethylbeta-dimethylaminopropyl ketone, ethyl beta-dimethylaminobutyl ketone,ethyl beta-dimethylaminoamyl ketone, ethyl beta-dimethylamiuohexylketone, etc., propyl beta-dimethylaminopropyl ketone, propylbeta-dimethylaminobutyl ketone, propyl beta-dimethylaminoamyl ketone,propyl beta-dimethylaminohexyl ketone, etc., butylbeta-dimethylaminopropyl ketone, butyl beta-dimethylaminobutyl ketone,butyl beta-dimethylaminoamyl ketone, butyl beta-dimethylaminohexylketone, etc., amyl betadimethylaminopropyl ketone, amylbeta-dime'thylaminobutyl ketone, amyl beta-dimethylaminoamyl ketone,amyl beta-dimethylaminohexyl ketone, etc., hexylbeta-dimethylaminopropyl ketone, hexyl beta-dimethylaminobutyl ketone,hexyl beta-dimethylaminoamyl ketone, heXyl beta-dimethy'laminohexylketone, etc., heptyl beta-dimethylaminopropyl ketone, heptylbeta-dimethylaminobutyl ketone, heptyl beta-dimethylaminoamyl ketone,heptyl beta-dimethylaminohexyl ketone, etc., octyl beta- 7dimethylaminopropyl ketone, octyl beta-dimethylaminobutyl ketone, octylbeta-dimethylaminoamyl ketone, octyl beta-dimethylaminohexyl ketone,etc.

Illustrative compounds in which R comprises an aryl group include phenylbeta-dimethylaminoethyl ketone (also namedbeta-dimethylaminopropiophenone), phenyl beta-diethylaminoethyl ketone,phenyl beta-dipropylaminoethyl ketone, phenyl beta-dibutylaminoethylketone, etc., phenyl beta-dimethylaminopropyl ketone, phenylbeta-diethylaminopropyl ketone, phenyl beta-dipropylaminopropyl ketone,phenyl beta-dibutylaminopropyl ketone, etc., phenylbeta-dimethylaminobutyl ketone, phenyl beta-diethylaminobutyl ketone,phenyl beta-dipropylaminobutyl ketone, phenyl beta-dibutylaminobutylketone, etc., phenyl beta-dimethylaminoamyl ketone, phenylbetadiethylaminoarnyl ketone, phenyl beta-dipropylaminoamyl ketone,phenyl beta-dibutylaminoamyl ketone, etc., phenylbeta-dimethylaminohexyl ketone, phenyl beta-diethylaminahexyl ketone,phenyl beta-dipropylaminoheiryl ketone, phenyl beta-dibut'ylaminohexylketone, etc.,

tolyl beta-dirnethylaminoethyl ketone, tolyl beta-diethylaminoethylketone, tolyl beta-dipropylaminoethyl ketone, tolylbeta-dibutylaminoe'thyl ketone, etc., tolyl beta-dimethylaminopropylketone, tolyl beta-diethylaminopropyl e ketone, tolylbeta-dipropylaminopropyl ketone, tolyl betadibutylaminopropyl ketone,etc., tolyl beta-dirnethylarninobutyl ketone, tolylbeta-diethylarninobutyl ketone, tolyl beta dipropylaminobntyl ketone,tolyl beta-dibutylaminob'utyl ketone, etc., xylylbeta-dimethylaminoethyl ketone, Xylyl beta-dimethylaminoethyl ketone,xylyl betadipropylaminoethyl ketone, xylyl beta-dibutylaminoethylketone, etc., xylyl beta-dimethylaminopropyl ketone, xylylbeta-diethylaminopropyl' ketone, xylyl beta-dipropylaminopropyl ketone,xylyl beta-dibutylaminopropyl ketone, etc., xylylbeta-dimethylaminobutyl ketone, xylyl beta-diethylaminobutyl ketone,xylyl beta-dipropylaminm aminoamyl ketone, cyclohexylbeta-diethylaminoamyl ketone, etc., cyclohexyl beta-dimethylaminohexylketone. cyclohexyl beta-diethylaminohexyl ketone, etc., cyclobutylbeta-dimethylaminoethylketone, cyclobutyl beta-di e'thylaminoethylketone, etc., cyclopropyl beta-dimethylaminoethyl ketone, cyclopropylbeta-diethylaminoethyl ketone, etc., other hydrocarbon groupsrepresented by R include alkenyl, aralkyl, etc.

While the dialkylamino compounds are preferred, it is understood that insome cases R1 and R2 may comprise carbon atoms of a cyclic group as, forexample, where R1 and h are carbon'atoms of a pyridine ring, qui'nolinering,

' isoquinoline ring, quinaldine ring, etc., or a pyrrole ring,

pyrroline ring, pyrrolidine ring, etc. In still another embodiment R maycomprise a substituted hydrocarbon group, the substituent containingoxygen, nitrogen and/or sulfur, including heterocyclic rings. However,it is understood that all of these compounds are not necessarilyequivalent.

While the novel process of the present invention is particularlyapplicable to the treatment of sour gasolines including cracked,straight-run and mixtures thereof, it is understood that the presentprocess may be used for the treatment of other hydrocarbon distillatesincluding cracked and/ or straight-run kerosene, diesel fuel, mineraloil, lubricating oil, fuel oil, etc. In another embodiment, the presentinvention may be utilized for thetreatment of gaseous fractionscontaining mercaptans. In still another embodiment the process may beutilized for the treatment of other fractions containing mercaptans andthus may include synthetic fractions formed from starting reactantscontaining mercaptans, either as an impurity or as the desired reactant.J The concentrations of beta-dialkylamino ketone to be 7 used willdepend upon the concentration of mercaptans in the fraction beingtreated. At least one mol of betadialkylamino ketone should be used permol of mercaptan to be converted. Preferably an excess ofbeta-dialkylamino ketone is used in order to ensure complete conversionof the mercaptans, and the excess may comprise up to 50 or moremolecular proportions of beta-dialkylamino ketone per molecularproportion of mercaptan.

The process of the present invention may be effected in any suitablemanner. In 'one' method, the beta-dialkylamino ketone iscommingled withthe petroleum distillate and the mixture is subjected to refluxing,distillation, etc. The temperature'will depend upon the particularfraction being distilled and may range from slightly above atmosphericto 600 F. or. more. The distillation may be efiected atatmospheric,subatmospheric or superatmospheric pressure which may be up to1000pounds per square inch or more. In another embodiment thebeta-dialkylamino ketone is commingled with the petroleum distillate andthe resultant mixture is passed through suitable mixing devices such asdurion mixers, orifices,

vgaseous fraction, the gaseous fraction may be passed through a body ofthe beta-dialkylamino ketone contained etc., and then introduced into astorage tank which, when in a suitable reaction vesse. It is understoodthat any other suitable method for efiecting reaction of thebetadialkylamino ketone with mercaptans may be utilized.

The following examples are introduced to illustrate further the noveltyand utility of the present invention but not with the intention ofunduly limiting the same.

Example I After refluxing, the portion containing beta-dimethylaminopropiophenone had a mercaptan sulfur content of 008% by weight. Theother portion, which did not contain the additive, had a mercaptansulfur content ofv 0.02% by weight. It will be noted that thebeta-dialkylamino ketone served to considerably reduce the mercaptancontent of the gasoline.

Example 1 1 Topped crude oil is subjected to non-catalytic'thermalcracking by being-heated to a temperature of 940" F. in a furnaceand'passed through a reaction zone and then into a flash zone whereinvapors separate from residuum. The vapors are withdrawn overhead fromthe flash chamber and are passed into a fractionating column to separatean overhead fraction'comprising gas and gasoline. Butylbeta-dimethylaminoethyl ketone is added to the vapors from the flashchamber before passing into the fractionating column. In thefractionating column the beta dialkylamino ketone will react with themercaptans and the reaction product will be retained in the bottoms fraction, thereby. resulting in an overhead gasoline fraction of reducedmercaptan content.

' Example 111 Example IV 7 Cracked gasoline having a m'ercaptan contentof 0.03% by weight may be treated with caustic-methanol solution toreduce the mercaptan content down to about 0.003%: by weight. To thethus treated gasoline, beta-dimethylaminopropiophenone is added withintimate stirring and the mixture is sent to storage. Thistreatmeutjvill serve to produce a sweet gasoline. Y

I claim as my invention: 7 I 7 l. A method of converting a mercaptanwhich comprises reacting the mercaptan with beta-dialkylamino ketone. Iv

2. A method of converting a mercaptan'which cornprises reacting themercaptanwith beta-dimethylaminopropiophenone.

3. A method of treating a sour petroleum distillate which comprisesreacting the mercaptans containedin said distillate with abeta-dialkyl'amino ketone. e

4-. A method of treating .a sour petroleum distillate which comprisesreacting the mercaptans containedm said distillate with abeta-dimethylamino ketone.

5. A method of treating a sour petroleum distillate which comprisesreacting the mercaptans contained in said distillate with abeta-diethylamino ketone.

6. A method of treating a sour petroleum; distillate which comprisesreacting the mercaptans contained in said distillate withabeta-dipropylaminqketone.. V 7. A method of treating a sour petroleumdistillate which comprises reacting the mercaptans contained in saiddistillate with a beta-dibntylamino ketone.

8. A method of sweetening a sour gasoline which comprises reacting themercaptans contained in said gasoline With a beta-diaikylamino ketone.

9. A method of sweetening a sour gasoline which comprises reacting themercaptans contained in said gasoline withbeta-dimethylaminopropiophenone.

10. A method of sweetening a sour gasoline which comprises reacting themercaptans contained in said gasoline with an alkylheta-dimethylaminoethyl ketone.

References Cited in the file of this patent UNITED STATES PATENTS

1. A METHOD OF CONVERTING A MERCAPTAN WHICH COMPRISES REACTING THE MERCAPTAN WITH N BETA-DIALKYLAMINO KETONE. 